Some things that make me feel like disconnecting, but obviously I don't due to the risk of being punished for doing so in ranked.
When you open a supply crate and some greedy teammate runs in front and swipes everything, (even one of my friends irl does this and thinks its perfectly okay).
When a teammate calls out an item, you call dibs, but the other teammate rushes in and takes it anyway. Like whats the point of having a dibs system if people are just going to do that. If you wanted it then you should have called dibs first.
Lifeline. I have been playing more of her recently. As far as I am concerned, she is a support role and so the care package is for the whole team. I don't expect to be handed the purple armor, it's first come first serve. If you don't want to play the support role then choose another character.
Source: https://www.reddit.com/r/apexlegends/comments/fa2isk/looting_etiquette/